Systems and methods for feature-based alert triggering are disclosed herein. The system can include memory including a model database containing a machine-learning algorithm. The system can include a user device that can receive inputs from a user; and at least one server. The at least one server can: receive electrical signals from the user device, the electrical signals corresponding to a plurality of user inputs provided to the user device; automatically generate input-based features from the received electrical signals; input the input-based features into the machine-learning algorithm; automatically and directly generate a risk prediction with the machine-learning algorithm from the input-based features; and generate and display an alert when the risk prediction exceeds a threshold value.

A computer network or data network is a telecommunications network which allows computers to exchange data. In computer networks, networked computing devices exchange data with each other along network links (data connections). The connections between nodes are established using either cable media or wireless media. The best-known computer network is the Internet.
Network computer devices that originate, route and terminate the data are called network nodes. Nodes can include hosts such as personal computers, phones, servers as well as networking hardware. Two such devices can be said to be networked together when one device is able to exchange information with the other device, whether or not they have a direct connection to each other.
Computer networks differ in the transmission media used to carry their signals, the communications protocols to organize network traffic, the network's size, topology and organizational intent. In most cases, communications protocols are layered on other more specific or more general communications protocols, except for the physical layer that directly deals with the transmission media.

Systems and methods for automated platform-based algorithm monitoring


Compositions including zinc compounds and select amino acids in a carrier base, and methods of skin treatment with such compositions, are described. The compositions are useful for healing skin and minimizing the irritation incurred from contact with the zinc compound without loss of zinc availability during absorption into the integument.

The present invention relates to zinc-containing compositions and methods for topical use of such compositions to treat cutaneous wounds, irritations, lesions, abrasions or the like. More particularly, the invention relates to zinc-containing compositions containing an amino acid to minimize external irritation from the zinc when applied to the skin without diminishing the amount of free zinc available for absorption.
The value of zinc in tissue growth and repair is well documented. Zinc is essential for the function of at least 70 enzymes and is involved in a variety of metabolic processes. Zinc is a limiting factor in the formation of RNA and DNA. Zinc is also a limiting factor in zinc-dependent enzymes such as RNA and DNA polymerases, deoxythymidine kinase, and reverse transcriptase, which are responsible for the regulation of RNA and DNA metabolism. Diminished zinc availability slows protein synthesis, thereby slowing the replication of cells and inhibiting tissue repair. Approximately half of the total body zinc content of 2-3 gm (based on an average 70 kg adult) is found in ossified tissues and is, therefore, not readily available for metabolic processes. Although the skin boasts a higher zinc concentration than most tissues (10 micrograms/g of tissue), this is quickly depleted during the regeneration process. It has been shown experimentally that the activity of deoxythymidine kinase in rapidly regenerating connective tissue decreases as early as six days after animals are placed on a zinc-deficient diet, demonstrating that an external supply of zinc for use in tissue repair is essential. In fact, zinc supplementation has been shown to markedly improve wound healing in zinc-deficient individuals, while topical zinc improves wound healing in zinc-deficient and in normal individuals.
Zinc salts are known to inhibit bacterial and viral growth. Ophthalmic preparations of zinc sulfate to treat herpetic keratitis have been recommended since 1943. Oral preparations of zinc citrate used to treat gingivitis and periodontitis have been shown to reduce plaque formation and inhibit bacterial growth. Oral preparations of several zinc salts have been shown to reduce the symptoms and duration of the common cold caused by rhinovirus, but they are unpalatable and cause mouth irritation and nausea. Until the development of a palatable and less irritating zinc salt-with-amino-acid formulation, patients often refused to continue treatment with the oral preparations containing zinc salts.
Successful topical treatment of skin infections and lesions with zinc salts is well documented. Topical zinc pyrithione is an effective anti-fungal, effective in treating Malassezia furfur, the causative agent in several skin disorders including pityriasis versicolor. Topical zinc pyrithione has also been used to treat psoriasis and dandruff by inhibiting the over-proliferation of cells characterized by these conditions. Application of a zinc chloride solution before and after UV exposure in hairless mice reduced the number of sunburn cells in the epidermis and was reported in 1976 as a successful topical treatment of basal cell carcinoma in a human patient. Erythromycinzinc lotion is sebosuppressive and potentially beneficial to the acneic patient.
Herpes of the lips occurs in 50% of the population, while genital herpes is now one of the most common venereal diseases. Zinc salts irreversibly inhibit herpes virus replication in vitro and are effective in treating herpes infections in vivo. Zinc ions irreversibly inhibit herpes simplex virus (HSV) glycoprotein functions by accumulating in the sulfhydryl groups of glycoprotein B in the viral membrane, blocking synthesis of DNA. In the closely related rhinovirus, it is theorized that free zinc ions also sequester in the membrane, inhibiting viral binding with ICAM receptor sites in mucous membranes. Other closely related viruses may similarly be affected by zinc ions. U.S. Pat. No. 5,545,673 cites in vitro evidence that HIV infectivity was reduced or completely eliminated when concentrated viral stocks were incubated with 1-1.5% zinc acetate for 2 hours. HSV has significant homology to varicella-zoster virus. Eruptions of herpes zoster are thought to be more frequent in the elderly not because of immune dysfunction, but because of slowed mobilization of the immune system. It follows that prompt treatment with a zinc salt would be extremely beneficial as it would markedly decrease viral load and painful lesions independent of immune system activation.
Zinc salt solutions applied to herpetic lesions decrease viral load and markedly improve healing rates, relieving the symptoms of herpes as healing occurs. Long-term topical application of zinc salt solutions appears to greatly reduce or eliminate recurrences of genital herpetic lesions as well as prevent post-herpetic erythema multiform. It has been postulated that the delivery of a high concentration (compared to natural tissue and body fluid levels of ionic zinc) of the virucidal agent to the infection site may prevent retrograde spread of virus along involved ganglia.
Zinc oxide has been shown in numerous studies to accelerate the healing of both chronic and acute wounds. This effect may be in part due to stimulation of epidermal basal cells, noted in mice, and in part due to increased insulin-like growth factor-1 and mRNA (messenger RNA), noted in granulation tissue of full-thickness wounds in domestic pigs. Zinc paste bandages containing inorganic zinc compounds, e.g., zinc sulfate and zinc oxide, have long been a standard treatment of venous stasis ulcers. Zinc chloride paste has been shown effective in debridement and formation of granulation tissue on chronic leg ulcers. Zinc oxide has been shown to promote cleansing and re-epithelialization of leg ulcers and to reduce infections and deterioration of ulcers.
Unfortunately, topical application of some zinc solutions can cause painful or irritating side effects if not used in very low concentrations. Zinc sulfate solutions of 0.2-1% can cause severe irritation, unpleasant dryness and stimulate the emetic reflex when applied circumorally.
Reports of dermal irritancy in animal dermal abrasion models examining wound healing show the following: 1% aqueous zinc chloride is severely irritant; 20% aqueous zinc acetate is slightly less irritant; 20% suspension zinc oxide, 1% aqueous zinc sulfate, and 20% suspension zinc pyrithione, are not overtly irritant. The less irritant zinc salts, such as zinc oxide (which is only slightly soluble in water), were only marginally effective in stimulating epidermal healing in comparison to the more irritating and more water-soluble zinc salts.
Further, it is interesting to note that in other studies the zinc solutions, particularly of zinc sulfate, do not maintain constant local concentration levels when applied to the skin as does zinc oxide. The zinc in these studies is not slowly solubilized to provide a constant level for absorption, being already in frank solution. This indicates that a zinc preparation that provides a higher concentration of solubilized zinc in a minimally irritating formulation allowing controlled absorption would be of great clinical value.
Compositions for treating various skin irritations are also known including zinc and another material or materials. Such are described, for example, in the following U.S. Patents:
U.S. Pat. No. 4,937,234 describes a pharmaceutically acceptable composition providing minerals(s) (e.g. Zn) in a bioavailable form by the inclusion of certain amino acids (see col. 2, lines 56-59), with the molar amount of an acidic mineral salt (e.g., zinc gluconate) to an amino acid (e.g., lysine) being from about 0.05M:1.0M to about 1.0M:0.05M and neutralized to a pH of 6-8. Zinc oxide is mentioned only as not being water insoluble. In Example 13, zinc oxide is solubilized in water by the addition of ascorbic-acid. Various skin irritations can be healed.
U.S. Pat. No. 4,711,780 describes a composition to treat surface epithelium to promote epithelial regeneration. The composition includes a mixture of a zinc salt, vitamin C, and a sulfur amino acid. Zinc oxide is not disclosed. The composition is stated to be useful in treating a wide variety of conditions, including of the skin, such as burns, cuts, fever blisters, poison ivy, chigger bites, diaper rash, genital herpes blisters, and sunburn. Depending on the locus of treatment, the composition will take different forms as appropriate, such as water, oil or gel vehicle; spray, or powder or medicated bandage.
U.S. Pat. No. 5,582,817 describes a composition for treating various skin diseases, see col. 6, lines 48-58. The composition includes a zinc salt, a zinc complex, or a salt of a zinc complex. The complex or salt thereof may be based on a zinc compound and an amino acid. Zinc oxide is mentioned and used only as a xe2x80x9crelatively insoluble metal saltxe2x80x9d. The co-use of a solubilizing agent is not disclosed. The composition is stated to have unexpected action in inducing metallothionen and suppressing the production of sunburn cells by UV rays.
U.S. Pat. No. 5,708,023 describes a composition for application to a surface (such as skin) including an irritant-inactivating agent and a substance which prevents the irritant-inactivating agent from binding to the surface. Pharmaceutically acceptable cationic substances may also be used to block.binding sites, e.g., cations from relatively soluble zinc and zinc salts (e.g., zinc gluconate, zinc acetate and zinc sulfate). Examples of other pharmaceutically acceptable cationic substances disclosed are quaternary ammonium compounds which are then further defined as including amino acids. This further characterization, however, of quaternary ammonium compounds is in error. While quaternary ammonium compounds have four (4) groups (none of which is hydrogen) attached to one (1) nitrogen atom, which then possesses a positive(+) charge of 1, all 21 natural and biologically important amino acids have the structure Rxe2x80x94CH(NH2)xe2x80x94COOH. Clearly amino acids do not satisfy the described cationic substance. Examples of irritants suitable for treatment include HIV and the hepatitis virus.
U.S. Pat. No. 5,260,066 describes a cryogel (a hydrogel containing PVA) bandage containing a therapeutic agent such as inorganic and organic zinc salts as antimicrobials, and amino acids such as glycine. Zinc oxide is not disclosed.
Many existing topical formulations are inadequate because they produce such local irritation that they are not easily tolerated. Others also frequently lack a sufficient effective concentration of zinc ion due to the low solubility of zinc oxide in the absence of suitable solubilizing agents. Further, existing formulations have unpalatable tastes, making circumoral application impractical.
It would be highly desirable to have a topical zinc formulation and method of use that addresses the deficiencies in existing treatments.
A primary object of the present invention is to provide a topical zinc composition for the management and healing of cutaneous wounds, irritations, abrasions and the like, including herpes-type lesions.
Another object of the invention is to provide a topical zinc composition that supplies a high effective concentration of available zinc and minimizes skin irritation.
Another object of the invention is to provide a topical zinc composition containing a select amino acid.
Another object of the invention is to provide a method of treating skin with a topical zinc composition containing a select amino acid.
The composition of the present invention includes (1) a pharmaceutically acceptable zinc compound, preferably zinc oxide or a divalent zinc complex, (2) a select amino acid, preferably glycine, and (3) a pharmaceutically acceptable carrier base, such as a solid.or semi-solid carrier base. The zinc compound is present in the carrier base together with a large excess of the amino acid (2 to 20 molar equivalents to the zinc) to provide a composition with high zinc ion availability and minimal skin irritance when topically applied to the skin.
A composition of the invention is used by applying the composition to an affected area of skin surface, and spreading the composition so as to contact and coat the area. Application to an affected area can be repeated periodically as needed until sufficient healing is achieved. The composition can also be applied to an occlusive or non-occlusive bandage. When the bandage is positioned on the skin, the composition contacts the skin to heal the affected area.
According to the present invention, it has been found that compositions containing a zinc compound; an appropriate carrier base, for example a cream, balm, lotion, water-bearing ointment or the like; and certain amino acids, in which the molecular ratio of amino acid to zinc is in the range of 2:1 to 20:1, causes minimal irritation while providing sufficient free zinc ions for local absorption into the integument and zinc availability for viral inhibition and healing. The composition contains from about 1 mg to about 20 mg of zinc for each gram of the composition.
Zinc compounds which can be used in combination with certain amino acids can be in any of the forms commonly used such as the sulfate, chloride, acetate, gluconate, ascorbate, citrate, aspartate, picolinate, orotate and transferrin salts, as well as zinc oxide and complexes of divalent zinc with an amino acid. It has been found that zinc oxide solubilized with glycine is particularly preferred.
Amino acids useful for the purpose of this invention are glycine, L-lysine, and D,L-lysine.
Suitable useful complexes are formed by reacting zinc oxide with monocarboxylic acids of the named amino acids and have the composition Zn(Amino Acid)2. These complexes are water-soluble, particularly in the presence of excess amino acid, release substantially all of the zinc as Zn2+ ion into aqueous solution, are minimally irritating because the amino acid modifies the irritant effect of the zinc, and have very good flavors, taste being an important consideration as the invention can be applied circumorally. However, amino acids, such as aspartic and glutamic acids, are not useful for forming the above complexes. These amino acids are dicarboxylic. Preferred complexes of divalent zinc with monocarboxylic amino acid are a zinc glycine complex having a formula Zn(C2H4NO2)2xc2x7nH2O in which n has a value of 1, 1xc2xd, or 2, combined with from 0.3 to 5.4 parts by weight of anhydrous glycine; and a zinc D,L-lysine complex having a formula Zn(C6H13N2O2)2xc2x74H2O combined with from 0.9 to 3.5 parts by weight of anhydrous glycine.
Preferred complexes of divalent zinc with monocarboxylic amino acid are a zinc glycine complex having a formula Zn(C2H4NO2)2.nH2O in which n has a value of 1, 1xc2xd, or 2, combined with from 0.3 to 5.4 parts by weight of anhydrous glycine; and a zinc D,L-lysine complex having a formula Zn(C6H13N2O2)2.4H2O combined with from 0.35 to 3.5 parts by weight of anhydrous glycine.
Appropriate carrier base compounds can contain components selected from a broad range of pharmaceutically acceptable materials known in the art of preparation of topical solid or semi-solid formulations, such as creams, moisturizing creams, lotions, emollients, balms and the like. Such a base formulation can include, but is not limited to purified water, sunflower oil, stearic acid, cocoa butter, monoglyceryl stearate, stearic triglyceride, stearyl alcohol, aloe barbadensis gel, jojoba oil, xcex1tocopheryl acetate (Vitamin E), carrot extract, jasmine extract, chamomile extract, calendula extract, red clover blossom extract, methyl paraben, propyl paraben, caramel, retinyl palmitate and fragrance oil.
It is important that no component of such base formulation possesses the potential for strong chelation of ionic zinc, for the presence of such compound will inactivate the zinc ions which provide the desired physiological benefit of availability for enzyme use to enhance tissue proliferation and healing as well as antiviral activity. The chemical principles which govern the chelation of metal ions by organic compounds are well known such that one skilled in the art can determine by visual inspection of a written chemical structure whether or not a given chemical compound has the potential for strong chelation of ionic zinc. (taking into account pH changes which can be caused by the base). It is well known, for example, that such varied structures as those represented by citric acid, tartaric acid, 8-hydroxyquinoline, orthophenanthroline, and ethylenediaminetetraacetic acid (EDTA), are structurally and electronically configured so as to form very tight, i.e. highly stable, chelated complexes with zinc ion. Thus, any structures which are chemical analogs of the aforementioned strong chelating compounds, or any others of of such compounds, are to be avoided in formulating the carrier base.
The compositions of the invention are also suitable for application to the skin by means of an occlusive or non-occlusive bandage or dressing. The compositions of the invention can be carried on a bandage in a conventional manner. When the bandage is positioned on the skin over an area to be treated, the composition comes into contact with the skin and acts on the skin in the same manner as described above in relation to directly applied compositions.
Thus, zinc-containing compositions prepared according to the present invention, include pharmaceutically acceptable zinc oxide and a select amino acid. The compositions possess a very pleasant flavor, modify the irritant effect of zinc, and release ionic zinc into a semi-aqueous solution and/or suspension at concentrations that are calculated to be on the order of one thousand times the normal blood level of zinc. The very high concentration gradient between available ionic zinc at the epithelial surface and the blood and tissue fluid zinc concentrations coupled with the effect of the components of the creams, balms, ointments, etc. (with respect to facilitation of the penetration of the zinc ions through the epithelial layer) provides the strong anti-viral and wound-healing enhancement properties of zinc to be made available where they are needed in order to effectively treat the skin.

Topical zinc compositions and methods of use


A semiconductor compound material, preferably a III-N-bulk crystal or a III-N-layer, is manufactured in a reactor by means of hydride vapor phase epitaxy (HVPE), wherein in a mixture of carrier gases a flow profile represented by local mass flow rates is formed in the reactor. The mixture can carry one or more reaction gases towards a substrate. Thereby, a concentration of hydrogen important for the reaction and deposition of reaction gases is adjusted at the substrate surface independently from the flow profile simultaneously formed in the reactor.

The present invention relates to a method of manufacturing semiconductor compound materials from a vapour phase, specifically of III-N-layers or III-N-bulk crystals as well as of standalone III-N-substrates, which are retrieved from III-N-bulk crystals.
The invention is further related to a corresponding device, i.e., a reactor, and further to specific III-N-layers, III-N-bulk crystals or standalone III-N-substrates which comprise specific properties.
Known semiconductor compound materials may be embodied as combinations of elements of the III. and V. main groups of the periodic table of the elements. An important representative is gallium arsenide (GaAs), which serves as a base material in high frequency techniques or opto-electronics. Particularly in the field of manufacturing opto-electronic components, such as blue LEDs (Light Emitting Diodes), specific attention has been drawn in recent years to the nitrides of these semiconductor compound materials, specifically gallium nitride (GaN).
The nitrides of semiconductor compound materials are known as III-N-materials. Therein "III" denotes at least one element of the III. main group of the periodic table of elements selected from aluminium, gallium and indium (in what follows abbreviated as Al, Ga or In), and "N" stands for the element nitrogen of the V. main group. These materials can be manufactured as standalone III-N-substrates, which are well-suited as base substrates for manufacturing opto- and micro-electronic components.
Regarding industrial applications, components for (Al, Ga, or In)N-based light emitting or laser diodes have commonly been grown on foreign substrates such as Al2O3 (sapphire) or SiC (silicon carbide).
Due to employing foreign substrates, however, disadvantages with regard to crystal quality may arise. The reason is that that crystal grids do not match well with each other. This may result in a reduction in durability and efficiency of the components.
One resort is represented by the growth on standalone III-N-substrates such as (Al, Ga, or In) N-substrates. The latter have, however, not been available in sufficient quality until present. The reasons for that substantially reside in difficulties related to conventional bulk growth technologies based on a melt, which are due to an extremely large equilibrium vapour pressure of nitrogen above III-N-compounds at typical growth temperatures. Even in the case of growing indium phosphate (InP), a pressure of about 30 bar develops at corresponding temperatures. The pressure of nitrogen would attain values of the pressure some orders of magnitude larger than that.
The presently commercially available method for growing (Al, Ga, In) N-substrates is the hydride vapour phase epitaxy (HVPE). The method has already been described in 1969 by H. P. Maruska and J. J. Tietjen (Applied Physics Letters 15 (1969) p. 327-329). With this method crystal growth out of sources of elements from the III. main group, which are present in a metallic state, and out of hydrogen compounds of elements of the V. main group is carried out.
As an example, gallium is exposed to hydrogen chloride (HCl) at high temperatures of about 800-900° C. in order to manufacture gallium nitride. This mixture reacts to form gallium chloride and then encounters ammonia (NH3) at even higher growth temperatures of about 1.000-1.100° C. in the vicinity of the substrate. Out of a corresponding reaction gallium nitride (GaN) is deposited on the substrate. A distinctive feature of the HVPE-method is the large growth rate of about 50-250 μm per hour at a comparatively sound crystallinity.
However, with regard to the formation of thin layers having a precise layer thickness homogeneity, the metal organic vapour phase epitaxy (MOVPE) currently prevails.
With concern to the HVPE-method there are currently substantially two variants available for growing (Al, Ga, or In) N-substrates:
The epitaxial growth of III-N-materials on foreign substrates from a vapour phase with subsequent separation from the foreign substrate, or
the growth of thick III-N-bulk crystals (so called boules) on a III-N-substrate by means of vapour phase epitaxy with subsequent separation of the bulk crystal, for example by means of sawing.
Regarding variant (a), there arises a problem of how the separation of the grown materials from the foreign substrate may be accomplished. M. Kelly et al. (Jpn. J. Appl. Phys. Vol. 38, 1999, p. L217-L219) propose to strip off a thick GaN-layer grown on a substrate containing sapphire (Al2O3) by means of hydride vapour phase epitaxy (HVPE) from that substrate. The sapphire substrates covered with GaN are irradiated with a laser beam for this purpose. Consequently, the GaN-layer at the boundary towards the sapphire substrate is locally thermally decomposed and thus strips off the sapphire substrate.
Alternatively, a wet chemical etching (e.g., of GaAs: K. Motoki et al., Jap. J. Appl. Phys. Vol. 40, 2001, p. L140-L143), a dry chemical etching (e.g., of SiC: Melnik et al., Mat. Res. Soc. Symp. Proc. Vol. 482, 1998, p. 269-274) or a mechanical lapping (e.g., of sapphire: H.-M. Kim et al., Mat. Res. Soc. Symp. Proc. Vol. 639, 2001, pages G6.51.1-G6.51.6) of the substrate may be carried out.
With regard to variant (b), Vaudo et al. in U.S. Pat. No. 6,596,079 A propose a growth method of crystal boules with lengths of more than 1, 4 or 10 mm in accordance with the HVPE-method. By wire sawing and further manufacturing steps, e.g., chemical-mechanically polishing, reactive ion beam etching or photo-electronic etching, the III-N-substrates are yielded from the bulk crystal. Moreover, Vaudo et al. in WO 01/68955 A1 describe III-N-bulk crystals and III-N-substrates produced by this technology.
In order to lead the reaction gases in the reactor chamber towards the substrate, so called carrier gases are utilized. These are substantially chemically neutral, serve to adjust a desired flow profile in order to localize the reaction gases towards the substrate, and prevent the reaction gases from a premature reaction as a consequence of parasitic deposition on the reactor walls or at inner component parts of the reactor chamber.
As carrier gases are known, for example, nitrogen, hydrogen (Maruska et al. and Motoki et al.; references see above) or alternatively argon (Melnik et al.). It is also known to mix carrier gases. For example, it has been proposed to mix hydrogen and nitrogen as carrier gases in an experimentally predetermined ratio in order to improve the crystal quality that can be obtained (C. Dam et al., J. Cryst. Growth 285 (2005) p. 31-40 and F. Habel, Annual Report 2003, Opto-electronics Department, University of Ulm, p. 77-80).
However, there also arises a problem that upon variation of the mixing ratio of hydrogen with regard to, e.g. nitrogen, the flow conditions within the reactor chamber may also change with a consequence, that the homogeneity of the distribution of growth rates across the substrate may vary (C. Dam et al. and M. Meyyappan et al., J. Vac. Sci. Technol. A16 (1998), p. 685-688). Thus, it becomes difficult to control a stable flow of gases within the reactor chamber simultaneously with the efficiency of the reaction.
The present invention thus has an object to provide a method with which the crystallinity and the homogeneity of the resulting crystals may be further improved.
The object is solved by a method for manufacturing a semiconductor compound material using vapour phase epitaxy in a reactor, comprising the steps of (a) determining a volume flow of a first carrier gas in a mixture to set a predetermined value for the concentration of hydrogen at a point near a surface of a substrate; and (b) compensating for an influence exerted from step (a) on a flow profile in the reactor by determining corresponding volume flow proportions of first and second carrier gases in the mixture. The object is also achieved by a method for manufacturing a III-N-layer or a III-N-bulk crystal by means of vapour phase epitaxy in a reactor, the reactor comprising a number of gas lines for introducing carrier and reaction gases, comprising the step of: introducing three carrier gases into the reactor using the gas lines; and wherein each gas line introduces at least one carrier gas.
The object is further obtained by a reactor for manufacturing a III-N-bulk crystal or a III-N-layer on a foreign substrate by means of vapour phase epitaxy, comprising: a number of inlets each for a gas line to be formed in the reactor; and wherein at least one of the gas inlets for forming the gas line comprises supply ports for at least three carrier gases to be introduced simultaneously.
According to the invention semiconductor compound materials—doped or undoped—semiconducting or semiisolating—are manufactured. In particular, III-V-crystals are formed. Preferably, the method is employed to form III-N-crystals. Particular advantages are obtained in the case of gallium nitride-(GaN)-crystals. Other specific compounds different from the definitions as stated above are also encompassed by the invention.
According to a first aspect of the invention a semiconductor compound material is manufactured by means of vapour phase epitaxy in a reactor, wherein in a mixture of carrier gases a flow profile represented by local mass flow rates is formed in the reactor. Therein, the mixture carries one or more reaction gases towards a substrate. Thereby, a concentration of hydrogen at the surface of the substrate being important for the reaction and deposition of the reaction gases may be adjusted independently from the flow profile that is formed within the reactor.
By adjusting the concentration of hydrogen independent from the flow profile, an arbitrary flow profile can be realized for a given concentration. The capability of freely adjusting the flow profile on the other hand also allows to adjust the partial flow profile of the reaction gases supplied to the substrate in an arbitrary manner.
Hence, while the concentration of hydrogen at the surface of the substrate is employed to optimise the crystallinity of the grown material, a desired layer thickness homogeneity is obtained by controlling the flow profile. Both ingredients can be handled largely independent from each other according to the invention.
The adjustment of the concentration of hydrogen can be performed for example by employing hydrogen and nitrogen as carrier gases. The proportion of hydrogen, or the ratio between hydrogen and nitrogen, is adjusted to directly influence the concentration of hydrogen at the crystal surface.
By means of nitrogen and a further carrier gas, for example argon, which has a specific carrier gas weight different from nitrogen, the flow profile can be influenced, such that the inevitable influence of the proportion of hydrogen in the carrier gas mixture on the flow profile is compensated.
On the one hand the flow profile depends on the dimensions and the shape of the inner space of the reactor, which may be cylindrical.
On the other hand the reactor may, for example, have concentric ring-like gas inlets in order to form carrier gas lines and reaction gas lines in the laminar stream. In case the gas inlets provide differing densities with regard to the gas lines which are inlet into the chamber at the respective radius positions, this condition will adversely exert an influence on the flow profile, which is dominated by the local mass flow rates (momentum flow).
By adjusting respective proportions of the volume stream, for example via a mixture ratio of the two further carrier gases being set to depend on the position of the currently considered carrier gas line, the desired flow profile can be obtained. It has been found, that the volume stream proportion of hydrogen does not necessarily have to be fixed to a predetermined mixture ratio with regard to nitrogen. Rather, that volume stream proportion may be selected being decoupled from this ratio. A lower amount of hydrogen (for example in order to reduce the H2-concentration) can be compensated by a larger amount with regard to the mixture ratio of the heavier carrier gas (e.g., argon) relative to the lighter carrier gas (e.g. nitrogen). As a result, the local mass flow rate and thus the flow profile can be maintained.
Similarly, the mass flow rate can be increased by adjusting the mixture ratio of the two heavier carrier gases, in order to vary the distribution of growth rates on the substrate. The hydrogen concentration at the substrate surface can thereby be maintained at a constant value.
According to a further aspect of the invention, a vapour phase epitaxy method is performed in a reactor, which has a number of gas lines which each may inlet carrier gases and partially reaction gases. In at least one of the gas lines of the reactor, a chemically inert carrier gas is simultaneously introduced—preferably during the growth phase—with hydrogen as well as nitrogen.
The first chemically inert carrier gas may be argon. Other carrier gases, particularly noble gases such as helium, etc. may be employed as well.
According to a method of the invention, the semiconductor compound material to be manufactured may be a III-N-crystal, particularly a III-N-layer on a foreign substrate or a III-N-bulk substrate.
The III-N-crystal to be manufactured may comprise gallium nitride, wherein the gallium nitride is formed in mono-crystalline manner due to a reaction of the introduced reaction gases with subsequent deposition on the substrate in the reactor.
As a substrate may be employed, for example: sapphire, silicon, silicon carbide, diamond, lithium gallate, lithium aluminate, zinc oxide, spinel, magnesium oxide, ScAlMgO4, GaAs, GaN, AlN, InN, AlGaN or InGaN.
Further aspects, advantages and embodiments are evident from the appended claims.
In the embodiments, an HVPE-arrangement is modified, such that at least one of the carrier gas lines is adjusted to carry a mixture of hydrogen, nitrogen and argon with respective volume stream percentages ranging from 0% to 100%.
FIG. 1 shows in a schematical representation an example of a basic configuration of a HVPE-arrangement in cross-section, to which the present invention may be applied. In the present case, a GaN-layer is to be deposited on a template, for example a foreign substrate or a GaN-substrate.
Prior to the growth procedure, the start or seed substrate 16 is provided. The GaN-substrate has for example a diameter of more than 5 cm at a (0001)-orientation, or at a slight inclination of the substrate surface against the exact (0001)-plane.
The HVPE-arrangement 20 includes a horizontal glass reactor 21 according to one possible embodiment, further a multi-zone furnace 22 enclosing the reactor, gas inlets 23, 23′ indicated by arrows and a pump and discharge system 24 also indicated by an arrow.
The GaN-substrate 16 is introduced into the reactor 21 through the load-unload flange 25 and positioned on a substrate holder 26. Using the pump and discharge system 24, the reactor is brought to the desired process pressure, suitably in the range of ≦1.000 mbar, for example to a pressure of about 950 mbar.
The multi-zone furnace has a first zone 22A, with which the growth temperature of the surface of the substrate is set, and a second zone 22B, with which the temperature in the area of a Ga-tray 28 is set. Via the gas inlets 23, 23′ Ar, H2 and N2 as carrier gases are inlet into the reactor. The gas inlets 23, 23′ each define one carrier gas line.
For the purpose of an in situ generation of gallium chloride (GaCl), gallium (Ga) provided in the Ga-tray is heated to, e.g., 850° C. by adjusting a suitable temperature in the zone 22B of the multi-zone furnace 22. The gallium is then processed with hydrogen chloride (HCl), which is supplied from the gas supply 23 together with the Ar/H2/N2-carrier gas in a suitable gas mixture ratio and under a suitable flow rate.
The gallium chloride (GaCl) generated in situ flows from the openings indicated in FIG. 1 at the end of the inflow tube 23 into the reactor 21, and is mixed there with ammonia (NH3), which is introduced from the gas inlet 23′ together with one of the two Ar/H2/N2-carrier gas mixtures in suitable gas mixture ratio and under a suitable flow rate for adjusting a desired NH3 partial pressure of, e.g. about, 6 to 7×103 Pa.
The chemical reaction of gallium chloride with ammonia (NH3) takes place in order to yield gallium nitride (GaN). Further, hydrogen chloride (HCl) as well as hydrogen (H2) are generated as side products, which leave the system together with the other carrier gases via the pump and discharge system 24.
At the surface of the substrate 16 the hydrogen generated as stated above contributes to a local concentration of hydrogen in conjunction with that hydrogen, which has been supplied as a carrier gas. This may influence the local behaviour of the reaction sustainably, since it increases for example the surface mobility of the species. Consequently, the volume flow rate of hydrogen introduced through both gas lines according to this embodiment may be adjusted to an optimised value, which may be experimentally determined. Such determination may for example be carried out by investigations of the surface morphology as provided in Habel (see above). The determined value of the volume flow portion necessary to achieve a target concentration of hydrogen will generally have to be derived for each reactor separately.
The local concentration of hydrogen is mainly determined by the supply of the carrier gas and only to a lesser degree by hydrogen as a side product of the reaction.
The volume flow rate of each gas line can be different from next one. This also depends on the flow profile in the reactor 20. In case the flow profile differs, or if the mass flow rates of both gas lines are not adapted to each other, then the mixture ratios of the other two carrier gases Ar and N2 are adapted to each other for each of the carrier gas lines associated with the gas inlets 23, 23′. The mixture ratios can particularly be different, such that the modification in the flow profile due to the adoption of the volume flow of H2 is just compensated.
As can be seen from the temperature profile in the bottom part of FIG. 1, a temperature is adjusted in the zone 22A of the multi-zone furnace 22 being comparatively larger than that of the zone 22B to achieve a substrate temperature suitably of about 950-1.100° C., e.g., about 1.050° C. In this embodiment GaN is deposited on the substrate holder.
If for example a (Ga, Al, or In)N—, a (Ga, Al)N— or a (Ga, In)N-layer is to be deposited instead of a GaN-layer, further trays for Al— and/or In have to be provided in the HVPE-arrangement 20. The inflow of corresponding aluminium and/or indium chloride into the reactor is effected by supply of HCl in a suitable carrier gas of for example H2/N2, analogously to what is shown in FIG. 1 by the gas inlet 23 for Ga.
FIGS. 2 and 3 show in schematical representation a second embodiment of a vertical reactor 10 in cross-sectional profile, which can be realized with the invention. Herein, a vertical AIXTRON HVPE-reactor is concerned for example. As in the previous embodiment, a crystalline layer of GaN is formed on a foreign substrate made from sapphire (template 7), for example.
After achieving the growth temperature, the III-N-crystal growth (i.e., of GaN) is started by connecting the supply of the group-III-source material (i.e., Ga). This means for example in the case of the GaN-bulk crystal growth, that hydrogen chloride gas is led over the gallium-source, wherein gallium chloride gas is yielded as in the first embodiment.
Prior to the start of the III-N-crystal growth, a suitable composition of hydrogen, nitrogen and argon is adjusted in the carrier gas lines. This step will generally last until stable gas flows have been formed. The corresponding compositions in the carrier gas lines are chosen on the one hand, such that at the substrate surface a concentration of hydrogen is provided which may achieve an optimum crystal quality.
On the other hand the respective portion of argon within the carrier gas lines ensures that a balancing of the respective momentum flows leads to a homogenous distribution of growth rates on the substrate. Therein, the effect of an additional use of argon is based on the fact that argon is heavier than nitrogen, whereas hydrogen is lighter as nitrogen. As a result the momentum flows can be balanced by varying the flow of argon with the proportion of hydrogen.
In addition to the connection to the supply of group-III-source materials (herein Ga) corresponding source materials intended for doping may selectively be connected for supply.
A modified embodiment of the AIXTRON HVPE-reactor will now be described: as a substrate 7 in this embodiment a GaN-substrate having a diameter between 50 and 60 mm may be chosen. The reactor is constructed such that not only in the separation line, which separates the ammonia and gallium chloride line from each other, but also in the peripheral wall purge line an arbitrary mixture of the three carrier gases hydrogen, argon and nitrogen can be adjusted. More specifically, the adjustment may concern each of the different volume flow rates, or the mass flow rates, respectively. The HVPE-process is carried out for example at a temperature of about 1.050° C. and at a pressure of 800 mbar with a V/III-mixture ratio of about 35.
The carrier gas flow in the separation line (gas inlet 2) amounts to 50 Vol.-% of hydrogen, 30 Vol.-% of argon and of 20 Vol.-% of nitrogen. The carrier gas flow in the peripheral wall purge line (gas inlet 4) is composed as follows: 53 Vol.-% hydrogen and 47 Vol.-% nitrogen. The mean growth rate amounts to about 220 μm/h and is determined by layer thickness mapping applying ellipsometry.
The layer thickness distribution has in this experiment been determined by mapping the surface by means of an in situ-ellipsometer M2000 by J. A. Woollam Co., Lincoln, Nebr., U.S.A. The pitch of measurement points in each two directions perpendicular with respect to each other on the surface amounted to about 5 mm. Therein, from each spectrum the ellipsometric parameters Psi and Delta have been used to determine the layer thickness by means of model simulation (cf. H. G. Thomkins et al. in "Spectroscopic Ellipsometry and Reflectrometry", Wiley, New York, 1989).
The homogeneity of the distribution of growth rates further determined thereby is defined by the statistical standard deviation of the measured layer thicknesses. The standard deviation amounts to less than 10% according to the invention, in one embodiment even less than 7%—with consideration of an edge exclusion area of 4 mm. Particularly note-worthy is the degree of a crystallinity yielded simultaneously with the layer thickness homogeneity, which will be detailed below.
In the concentric, vertical construction as shown in FIGS. 2 and 3 the flow profile is dominated by the momentum, i.e., masses and flow rates of the gases discharged from the individual gas inlets. If for example a comparatively heavy gas such as nitrogen flows in the peripheral purge line and a comparatively light gas such as hydrogen flows in the inner separation line, then the nitrogen urges inwards resulting in a convex growth rate profile, since the largest growth rate is obtained in the substrate centre. According to the invention, argon or another heavy gas may be provided additionally in the separation line for example, in order to re-shape the growth profile towards a concave form. The effect is caused by the larger mass of the gases flowing inwards.
In a reverse case, a third, lighter gas can be provided in the peripheral wall purge line as a carrier gas.
The effect of argon may be explained as follows: by the larger mass of argon as compared with nitrogen, the momentum flow of an outer nitrogen dominated gas line can be compensated by adding argon to hydrogen in an inner gas line. Consequently, a constant homogeneous growth rate profile may be achieved.
Basically, this would also be accomplished by varying only the ratio of N2 to H. However, this ratio is fixed ("pinned"), since the H2-concentration, or the ratio relative to N2 at the surface of the substrate, has to attain a predetermined value in order to obtain an optimum crystal quality.
An exemplary sequence of steps according to the method of the invention is shown in FIG. 4. On the left side of the chart, the sequence of steps substantially reflects what has been detailed in the above two embodiments. The individual steps are partly to be understood as processes overlapping each other in time. For example, the carrier gases are introduced prior to the reacting gases, but the respective flows are of course maintained during the growth phase.
On the right side of FIG. 4, the determination of the volume flow proportions for the three carrier gases is schematically represented. A target concentration of H2 at the surface is preset. From this value, a volume flow portion of H2 in the gas line(s) is derived, which is necessary in order to achieve the target concentration. The relation can be calculated by means of simulating the flows at the substrate surface.
The simulations may also include the determination of the volume flow proportions of N2 and Ar. The basic principle is to achieve a flow profile as a target value. By adjusting the volume flow proportions of N2 and Ar (e.g., as compared with standard settings for these values) which may represent free parameters, a deviation from the target profile due to the calculated H2-volume flow proportion may be compensated. The dashed lines in FIG. 4 indicate that optionally an iterative process may be required.
The determination of the concentrations and flow profiles by experiment and measurement and the adjustment of the volume flow portions responsive thereto is basically encompassed by the invention.
In a further embodiment of the invention, a III-N-substrate having a c-, a-, m- or r-plane as the growth plane is used as the substrate, and the III-N-bulk crystal is deposited on the selected growth plane.
In a further embodiment of the invention a III-N-substrate having a growth plane is used, which is inclined relative to the c-, a-, m- or r-plane by 0.1-30°, wherein the III-N-bulk crystal is deposited thereupon.
In a still further embodiment of the invention, a doped III-N-substrate is used as the substrate. On the substrate a doped III-N-bulk crystal is deposited, wherein as dopants each one element is employed selected from the group comprising silicon, tellurium, magnesium and iron.
According to the invention single crystalline sapphire, silicon carbide, gallium arsenide, lithium aluminate or silicon can further be used as the substrate. The III-N-bulk crystal is then deposited on this substrate. In a particularly preferred embodiment GaN-substrate is used as the substrate in free-standing form or in template-form, and a GaN-bulk crystal is then grown according to the invention.
After the method according to the invention has been carried out, freestanding III-N-crystal substrates can be manufactured in a simple manner by separating one or more III-N-substrates from the III-N-bulk crystal. A particularly suited method for separation is represented by wire-sawing. Adjacently, further processing steps may follow, particularly lapping, polishing, thermal post processing and/or arbitrary final cleaning steps.
According to the invention there is further provided a III-N-bulk crystal, which is available according to the method of the invention. Preferably, the crystal is manufactured according to the methods as provided in the appended claims or in the present embodiments. In conjunction with the bulk crystal also the single crystal obtained by separation due to wire- or inner hole-sawing inherits the excellent characteristics with concern to crystallinity and layer thickness homogeneity.
A correspondingly manufactured III-N-crystal surprises by its unique crystallinity. This also holds true for the correspondingly separated, free-standing III-N-substrates. Particular emphasis has to be laid on the effect, that the crystallinity is obtained simultaneously and in combination with a high layer thickness homogeneity. As explained above with reference to the embodiments, the layer thickness homogeneity according to the invention amounts to less than 10%, in one embodiment even less than 7% in consideration of an edge exclusion area of 4 mm.
The crystallinity of the crystal can be defined particularly by means of rocking-curve mapping and/or by micro-raman-mapping.
Therein, the spatial distribution of absolute positions or the full-widths half-means of the X-ray diffraction curves corresponding to the diffraction at predetermined grid plane bands is recorded for example by means of X-ray diffraction in metrological manner. The homogeneity of the crystal quality (crystallinity) in the growth plane may in the case of rocking-curve mapping be examined by recording of ω-scans at distinct probe locations. The co-scan is recorded within a plane parallel to the growth plane. In the case of growth in [0001]-direction the reflection of the (0002)-grid planes can be used for the co-scans.
The homogeneity of the crystal quality in the growth direction, however, may be determined by means of the standard deviation of the mean values of the full-width half-means of the (0002) co-scans of individual substrates obtained from corresponding III-N-bulk crystals.
Alternatively, the homogeneity of the crystal quality in the growth direction can be determined by the rocking-curve-mapping, which is recorded within a plane including the growth direction. Regarding the growth in [0001]-direction, the reflection at an m-plane selected from {1100}, or from {(1010), (0110), (1100), (0110), (1100)} respectively, may be utilized with the Ω-scans. The mapping is performed on a corresponding m-plane or a plane which is slightly inclined with respect to the corresponding m-plane by an inclination angle between 0 and 10°.
A second method for determining the homogeneity of the crystal quality relates to micro-Raman-mappings. For example the standard deviations of the frequency and the full-width half-mean of the E2-phonon of a scan on an area parallel to the growth plane, or along the growth direction, represent a measure for the homogeneity of the crystal quality in corresponding directions. The homogeneity of the crystal quality of the bulk crystal in growth direction is preferably determined by the standard deviation of the mean values of the full-width half-mean of the E2-phonon of the individual substrates, which have been obtained from the corresponding bulk crystal.
The following results have been obtained for a crystal grown according to the invention:
In a rocking-curve mapping of a III-N-bulk crystal according to the invention of an area parallel to the growth plane, the standard deviation of respectively measured full-width half-mean values amounts to 5% or less, in exceptional cases 3% or less. Within an area extending along the growth direction the full-width half-mean amounts to 10% or less, in exceptional cases 7.5%, and in particularly exceptional cases 5% or less.
The standard deviation has been determined by performing at multiple measurement points, for example 100 points, in those areas intended to be measured each a measurement for the rocking curve-mapping. Of all measurements a mean value of the full-width half-means has been calculated and the standard deviation has been derived with respect to that mean value via a common statistical analysis.
Alternatively, the crystallinity could be determined via a micro-Raman-mapping of the III-N-bulk crystal on a plane parallel to the growth plane and/or along growth direction. The standard deviation of the measured full-width half-means of the E2-phonon is then provided. In the first case (area parallel to the growth plane) the standard deviation amounts to 5% or less, in exceptional cases 3% or less, in particularly exceptional cases 2% or less. In the second case the standard deviation amounts to 10% or less, in exceptional cases 7.5% or less, and in particularly exceptional cases 5% or less. The measurement has been carried out analogously to that of the rocking-curve mapping over, e.g., 100 measurement points.
The values provided with regard to crystallinity hold particularly true for the obtained GaN-crystals. It shall be repeatedly emphasized herein the combination of the excellent values for crystallinity with those for the layer thickness homogeneity, which may be obtained according to the invention.

Method and device for manufacturing semiconductor compound materials by means of vapour phase epitaxy


The butt end of a standard pool cue is modified by boring a threaded receiving female hole through the center of the butt cushion. A male threaded stub of an extender is sized to fit the butt end of a pool cue, which extender has, at its forward end, a cavity to receive the butt cushion and a center-located threaded bolt that is sized to mate with a threaded bore in the center of the cue cushion. One or more butt extenders are adapted at the butt end to receive other extender sections.

The field of the present invention relates to pool cues and extenders for same. Further, the field of this pool cue invention relates to one that has one or more butt extenders that may easily and quickly be attached to a standard cue for breaking a rack of cue balls or for play in places having limited space.
My invention interfaces and operates in conjunction with pool cue apparatus for playing the sport of pool. Provided below are brief descriptions of certain relevant terms which further the understanding of the invention and provide a basis for a detailed teaching of the improvement in the art provided by this invention.
Pool Cues
All pool cues whether one piece or detachable for ease of carrying and handling have both a tip and a butt end. On the butt or base end a cushion is normally attached by a screw with the cushion serving to protect the cue from damage when same comes into contact with the floor. This invention modifies the butt end of a standard pool cue by boring a threaded receiving female hole through the center of the butt cushion where it is ready to receive a male threaded stub of an extender.
Butt Extender
An extender is sized to fit the butt end of a pool cue and has at its forward end a cavity to receive the butt cushion and a center-located threaded bolt that is sized to mate with the threaded bore in the center of the cue cushion. One or more butt extenders may be connected in tandem in that some of the extenders are adapted at the butt end to receive other extender sections.
The game of pool, whether at pastime or professional level, requires various cue sizes, weights and capabilities. Each pool player has his own cue that may be one piece or more often is a sectional device for ease of handling and carrying. Each cue in a ready to play condition has a tip and a butt end.
For the casual player - particularly at home - the pool table may be placed in a crowded area that requires dexterity and inventiveness to carry out some shots around posts and other obstructions surrounding the pool table. One or more extender sections of this invention may take the place of the butt section of a modified pool cue for use in such tight space environments. Such a cue is referred to as xe2x80x9cmodifiedxe2x80x9d in that its cushion and base end must be adapted to the inventive principles mentioned above under the pool cue and butt extender definitions.
Turning now to the prior art, a search was done by the patent Office for the parent design application and the Examiner cited some art of peripheral relevance. The examination and allowance of the earlier parent application resulted in citation of the following patents.
U.S. Pat. No. 4,526,370 to Mortellacci (July, 1985)
U.S. Pat. No. 5,407,197 to Parsons (April, 1995)
U.S. Pat. No. 5,665,003 to LeBeau (September, 1997)
U.S. Pat. No. 6,117,019 to Taylor (September, 2000)
U.S. Design Patent D-370,955 to Fisher (June, 1996)
The above listed patents have only a very limited relevance and do not achieve either the structure or the functions of the invention as disclosed and claimed herein.
The advantages and inventive nature of my apparatus and method over the aforementioned body of prior art is significantly two fold. First, a user can effectively attach one or more extenders to a modified pool cue. These extenders can vary the usable length and weight of a pool cue so adapted.
Additionally, should a user want to achieve a heavy weighted cue for breaking a rack of balls, the extender series each have cavities that house a user-selected series of weight rings so that a user""s particular break requirements may easily and quickly be met by use of my invention.
The butt extender of this invention fits over the butt end cushion of a pool cue and is adaptable for play in tightly obstructed table areas. Moreover the butt extender has the capability of regulating the weight in the extender portions by a series of weight rings. My method invention includes the novel steps of placing a bore in the center of a butt end cushion in order to receive an extender section that has a male threaded post to mate with the threads of the bore, which extender has a cushion-receiving void that houses the butt cushion of the cue.
My pool cue extender may consist of a series of extender sections of differing lengths. Such extenders are adapted to threadably fit within a modified prior art pool cue. That cue has, at its butt end, a cushion that has been bored centrally along the longitudinal axis of the cue. The inner surface of that bore is threaded to mate with a longitudinally aligned and threaded extender stub which protrudes from the front of an extender section. A cushion-receiving cavity surrounds the stub and is adapted to house the cue cushion when the extender has been added to the modified pool cue.
Further, my extender invention provides a deep elongated cushion-receiving cavity to additionally receive and house a series of washer-like weight rings, some of which have slightly oversized openings that may be dropped over the threaded extender stub before the extender itself is screwed unto the modified pool cue. The outermost weight ring is also threaded such that the extender houses and conceals both the cue cushion and the user-selected weight rings when in an attached condition for play.
Further yet, my extender comes in a series of differing lengths so that any user may select the length and weight that suits him for playing pool. The extender unit may easily and simply be added or removed from the cue without disrupting play and may be carried within the users pocket or case for convenience sake.
It is an object to provide a longitudinal and threaded bore through the butt cushion of a pool cue in order to modify the cue so that it may receive my extender invention.
It is an object to provide a series of extender sections that may be installed by a user on a pool cue in order to vary the weight and the length to suit that particular user.
It is an object to provide a series of both threaded and unthreaded weight rings that may be housed in a forward or rearward facing cavity which is provided at either end of an extender section.
It is an object to provide for simple hand attachment/removal of pool cue extenders to conceal and house a pool cue cushion in a forward facing cavity of an extender.
It is an object to provide a weight ring spanner wrench that allows the user to tighten threaded weight ring(s) around a protruding stub of an extender.
It is an object to provide a method and apparatus which easily and simply adjusts the length and weight of a pool cue by use of a series of extender and weight ring combinations.

Butt extender having a cushion-receiving cavity for a pool cue